Positive or Negative Pump

In my conventional gravity fed system, the water tank is in the loft and the hot water cylinder is in the airing cupboard on the landing. My shower mixer will need to be fed from above so this means the shower head and some pipework will be approx 200mm below the bottom of the cold water tank. If I mount the shower pump on the floor in the airing cupboard this means the pump will be about 8 feet below the water tank. If I then bring the outlet pipework back up to the loft and then to the shower, will I need a positive or negative pump? Many thanks, COLIN
Asked 4 years ago by Mr Colin Tansley, Southampton
The important distance is the distance between the bottom of the cold water tank and the top of the shower head.

Regardless of what the manufactures say we know from practical experience you need at least 600mm better with 750mm between the top of the shower head and the bottom of the tank for a positive head pump to work, so in your case definitely a neg head pump and you will have no problems.

Answered 4 years ago by George Thomson

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